Commit 748a76b5 authored by Richard Henderson's avatar Richard Henderson Committed by Matt Turner
Browse files

alpha: Implement atomic64_dec_if_positive 



Reviewed-and-Tested-by: default avatarMatt Turner <mattst88@gmail.com>
Signed-off-by: default avatarMatt Turner <mattst88@gmail.com>
Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
parent 6da75397

arch/alpha/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ config ALPHA 
	select ARCH_WANT_OPTIONAL_GPIOLIB

	select ARCH_WANT_IPC_PARSE_VERSION

	select ARCH_HAVE_NMI_SAFE_CMPXCHG

	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_CMOS_UPDATE

	select GENERIC_STRNCPY_FROM_USER

arch/alpha/include/asm/atomic.h

+28 −0
Original line number Diff line number Diff line
@@ -238,6 +238,34 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) 
	return !c;

}



/*

 * atomic64_dec_if_positive - decrement by 1 if old value positive

 * @v: pointer of type atomic_t

 *

 * The function returns the old value of *v minus 1, even if

 * the atomic variable, v, was not decremented.

 */

static inline long atomic64_dec_if_positive(atomic64_t *v)

{

	long old, tmp;

	smp_mb();

	__asm__ __volatile__(

	"1:	ldq_l	%[old],%[mem]\n"

	"	subq	%[old],1,%[tmp]\n"

	"	ble	%[old],2f\n"

	"	stq_c	%[tmp],%[mem]\n"

	"	beq	%[tmp],3f\n"

	"2:\n"

	".subsection 2\n"

	"3:	br	1b\n"

	".previous"

	: [old] "=&r"(old), [tmp] "=&r"(tmp)

	: [mem] "m"(*v)

	: "memory");

	smp_mb();

	return old - 1;

}



#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)



#define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)